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huda bio > Homeostasis > Flashcards

Homeostasis Flashcards

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1
Q

What is homeostasis?

A

The regulation of the internal conditions of a cell or organism to maintain
optimum conditions for function in response to internal and external
changes.

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2
Q

3 Examples of conditions maintained by homeostasis?

A

Blood Glucose Concentration
Body Temperature
Water Levels

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3
Q

Two types of responses used by the body’s control systems?

A

Chemical
Nervous

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4
Q

What 3 components do all control systems have?

A

Coordination Centres
Receptors
Effectors

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5
Q

Function of a receptor?

A

Detects a change in the environment (stimuli)

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6
Q

Function of a coordination centre?

A

Receive and processes information from receptors.

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7
Q

Function of an effector?

A

Bring about a response to a stimuli to restore optimal levels.

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8
Q

2 effectors?

A

Muscles
Glands

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9
Q

Function of the nervous system?

A

Allows the body to react to its surroundings and coordinate an appropriate response.

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10
Q

How does a stimulus lead to a response by the body?

A

Stimulus is converted to an electrical impulse by the receptor.
The electrical impulse passes along the sensory neurone to the CNS.
The CNS creates an appropriate response and an electrical impulse is sent along motor neurones to the effectors which carry out a response.

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11
Q

Sequence of the nervous system?

A

Stimulus -> Receptor -> Coordinator -> Effector -> Response

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12
Q

What is a reflex action?

A

Automatic and rapid response not involving conscious input from the brain.

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13
Q

Why are reflex actions important?

A

To aid survival by preventing harm to the body.

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14
Q

Describe a reflex arc?

A

Stimulus detected by a receptor.
Electrical impulse passes along a sensory neurone to the spinal cord.
At a synapse between a sensory and relay neurone, a chemical diffuses across the gap and stimulates a new impulse that passes along the relay neurone.
The same process occurs at a synapse between the relay and motor neurone.
At the effector, an appropriate response is carried out.

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15
Q

Difference between a reflex pathway and a conscious pathway.

A

In a reflex pathway the coordination centre is a relay neurone in the spinal cord/unconscious parts of the brain.
In a conscious pathway the coordination centre is in the conscious part of the brain.

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16
Q

What is a hormone?

A

A chemical messenger secreted by a gland. It travels to a target organ where it causes a response.

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17
Q

What does a gland do?

A

Secretes hormones into the bloodstream.

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18
Q

What gland controls all other glands in the body?

A

Pituitary gland.

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19
Q

Role of the pituitary gland (3)

A

Controls human growth
Stimulates the thyroid gland
Stimulates the production of oestrogen in ovaries

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20
Q

Role of the thyroid gland (3)

A

Secretes thyroxine
Controls metabolism
Controls heart rate

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21
Q

Role of the pancreas (2)

A

Secretes insulin
Controls blood glucose concentrations

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22
Q

Role of the adrenal gland (2)

A

Secretes adrenaline
Stimulates fight or flight response

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23
Q

Role of the ovaries (3)

A

Secretes oestrogen
Coordinates the menstrual cycle
Develops female secondary sexual characteristics

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24
Q

Role of the testes (3)

A

Secretes testosterone
Develops male secondary sexual characteristics
Coordinates the production of sperm

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25
Q

What happens when the blood glucose concentration is too high?

A

Pancreas secretes insulin.
Insulin binds to the receptors on muscles and liver.
Causes excess glucose to be converted to glycogen and stored.

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26
Q

What happens when the blood glucose concentration is too low?

A

Pancreas secretes glucagon.
Glucagon binds to liver cells.
Glycogen gets converted to glucose.
Glucose released into the blood.

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27
Q

How is blood glucose controlled using a negative feedback loop?

A

When the blood glucose concentration rises or falls below the optimum a hormone (insulin or glucagon) is secreted by the pancreas. The hormone brings the concentration back to its optimum.

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28
Q

What is Type 1 Diabetes?

A

Where the pancreas cant produce sufficient insulin to control blood glucose concentration.

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29
Q

Symptoms of Type 1 Diabetes? (3)

A

Excessive urination
Tiredness
Weight Loss

30
Q

Treatment of Type 1 Diabetes?

A

Insulin injections before meals
Limiting carbs intake
Pancreas transplants

31
Q

What does insulin injections do?

A

They allow the glucose to be converted to glycogen before a meal.

32
Q

What is Type 2 Diabetes?

A

A disorder where the body’s cells don’t respond to insulin leading to an uncontrollable blood glucose concentration.

33
Q

Risk Factors of Type 2 Diabetes? (2)

A

Obesity
Increasing Age

34
Q

How can Type 2 Diabetes be treated? (4)

A

Regular Exercise
Losing Weight
Carefully Controlled Diet
Drugs increasing insulin effectiveness and production

35
Q

What is the menstrual cycle?

A

Shedding of the uterus lining and ovulation.

36
Q

Events of the menstrual cycle?

A

Uterus lining thickens.
Egg begins to mature in the ovaries.
Egg is released (ovulation)
Uterus lining remains thick.
If egg is fertilised, pregnancy can occur.
If egg isn’t fertilised the egg and uterus wall breaks down.

37
Q

What is ovulation?

A

Release of a mature egg from ovaries. Every 28 days roughly.

38
Q

Four main hormones in menstrual cycle?

A

FSH
LH
Oestrogen
Progesterone

39
Q

Role of FSH?

A

Secreted by the pituitary gland.
Controls the maturation of eggs within the ovaries.
Triggers the production of oestrogen by the ovaries.

40
Q

Role of Oestrogen?

A

Produced by the ovaries.
Released due to FSH.
Causes the regrowth of the uterus lining.
Triggers the production of LH.
Restricts the release of more FSH.

41
Q

Role of LH?

A

Produced by the pituitary gland as a result of oestrogen.
Triggers ovulation (release of an egg).

42
Q

Role of progesterone?

A

Sustains the uterus lining.
Prevents the production of LH/FSH.

43
Q

Two types of oral contraceptives?

A

Combined contraceptive pill (contains oestrogen and progesterone)
Mini pill (only progesterone)

44
Q

How does the contraceptive pill prevent pregnancy?

A

Inhibits FSH so eggs don’t mature.
Increases the thickness of cervical mucus which immobilises the sperm cells.

45
Q

What is the contraceptive patch?

A

Contains progesterone and oestrogen. Placed on the skin for 7 days at a time.

46
Q

What is the contraceptive implant?

A

A small rod inserted under the skin that continuously releases progesterone and it lasts for 3 years.

47
Q

What is the contraceptive injection?

A

An injection containing progesterone that lasts 3 months.

48
Q

What is the IUS (intrauterine system)?

A

A small plastic device inserted into the uterus. It releases progesterone which thickens the cervical mucus and prevents the build up of the uterus lining.

49
Q

What is the IUD?

A

Inauterine device, small copper containing device inserted into the uterus. Prevents the implantation of embryos.

50
Q

What is a spermicide?

A

Chemical that kills or immobilises sperm cells.

51
Q

What is a barrier method?

A

Physical separation between the sperm and egg.

52
Q

Examples of barrier methods (2)

A

Diaphragm
Condom

53
Q

What is a condom?

A

Thin sheath worn on the penis or inside the vagina. It prevents STIs but may tear or break.

54
Q

What is a diaphragm?

A

A thin cap placed over the cervix that prevents the entry of sperm

55
Q

Surgical method of contraception?

A

Sterilisation (vasectomy) the sperm ducts are tied. In females the oviducts are tied.

56
Q

What is IVF?

A

In vitro fertilisation is when:
The mother is given FSH and LH which stimulates the maturation of eggs and ovulation.
Eggs are fertilised using sperm in a laboratory.
Develops into embryos
1 or 2 embryos are inserted into the woman’s womb.

57
Q

Advantages of fertility treatment? (2)

A

Can store a woman’s eggs for later.
Helps infertile couples have children.

58
Q

Disadvantages of fertility treatment? (3)

A

Expensive
Can result in twins
Low success rate especially for older couples.

59
Q

What is negative feedback?

A

The body responds to an increase or decrease in a factor by returning it to its optimum level.

60
Q

What is thyroxine?

A

Released by the thyroid gland.
Triggered by TSH (thyroid stimulating hormone).
Controls metabolic rate, growth and development.

61
Q

Negative Feedback in Thyroxine?

A

Receptors in the brain detect a fall in the levels of blood thyroxine.
Pituitary gland releases TSH.
More thyroxine is produced and released by the thyroid gland.
Blood thyroxine returns to normal.

62
Q

What is adrenaline?

A

Released in times of stress.

63
Q

Effects of adrenaline? (5)

A

Dilated pupils.
Stored glycogen converts to glucose.
Increased mental awareness
Increase in heart and breathing rate.
Delivers glucose and oxygen to the body.

64
Q

Function of homeostasis?

A

Maintain optimal conditions for enzyme actions and all cell functions.

65
Q

What is reaction time?

A

The time taken to respond to a stimulus.

66
Q

3 factors affecting reaction time?

A

Age
Stress
Use of drugs (caffeine)

67
Q

Independent variables for reaction time?

A

Caffeine or background music

68
Q

Control variables for reaction time?

A

Catching it with the dominant hand.
Dropping the same ruler from the same height each time.
No caffeine before experiment.

69
Q

How to make the reaction time practical more accurate?

A

Measure it in milliseconds.

70
Q

Estimated population size equation?

A

Total area/area sampled x number of plant counted.

71
Q
A

huda bio (8 decks)

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